The plot of residuals in Exercise 41 shows an outlier that wasn’t as evident in the data. The outlier is September 2001. Clearly, this wasn’t a typical month for air travel. Here are three models fit to this series, a single exponential smooth, a 12-point moving average, and the fitted values from the seasonal regression model of Exercise 41. Discuss how each deals with the outlier.
The remaining exercises require the use of statistics software. Statistics packages vary in their capabilities and in the default decisions that some make. As a result, depending upon which package you choose, your answers may differ from those in the back of the book.
Answer to relevant QuestionsQuarterly e-commerce retail sales (in millions of dollars) in the United States are provided. Use this time series to answer the following questions. a) Fit a linear trend model to this series but do not use the last two ...Return to the oil price data of Exercise 47. a) Find a linear model for this series. b) Find an exponential (multiplicative) model for this series. c) For the model of Exercise 47 and the models of parts a and b, compute ...For the Apple prices smoothed in Exercise 5, the actual value for January 2007 was 1.034. Find the absolute percentage error of your forecast. The investment club described in Exercise 4 decided to repeat their experiment in a different way. Three members of the club took responsibility for one of each of the three investment “strategies,” making the final ...An industrial machine requires an emergency shutoff switch that must be designed so that it can be easily operated with either hand. Design an experiment to find out whether workers will be able to deactivate the machine as ...
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